CSV to JSON Converter — Headers, Nesting & Big Files
Convert CSV (Comma-Separated Values) to JSON format instantly with our free browser-based converter. Paste your CSV data or upload a file, and get properly formatted JSON output. The converter automatically detects headers and creates JSON objects with key-value pairs.
Supports tab-separated (TSV), semicolon-separated, and custom delimiters. All processing happens in your browser — your data never leaves your device.
Real-world CSV is messier than the format suggests, and the parser is built for that: quoted fields containing commas, escaped double quotes, line breaks inside a cell, a BOM at the start of a file exported from Excel, and semicolon delimiters from European locales are all handled rather than producing a silently misaligned result. Numbers and booleans can be typed or kept as strings, which matters when a column of ZIP codes or phone numbers must not lose its leading zero.
How to use CSV to JSON
- Paste your CSV data into the left input area.
- Adjust options like headers vs. no-headers, or custom delimiters if needed.
- Click Convert to see the JSON output on the right.
- Use the Copy or Download buttons to save the result.
Features
- Auto-detect headers as JSON keys — Treat the first row as property names automatically.
- Support for TSV and custom delimiters — Handles CSV, TSV (tab-separated), semicolons, and more.
- Nested objects from dotted headers — A column named user.name becomes { "user": { "name": … } } when nesting is on.
- Open a file — Load a .csv or .tsv straight from your computer; nothing is uploaded.
- Pretty-print or minified JSON output — Format your JSON exactly how you need it.
- Handle quoted fields and escaped characters — Properly parses complex CSV data.
- Download result as .json file — Save the output directly.
- 100% client-side processing — Perfect for private or sensitive data.
Frequently Asked Questions
How do I convert CSV to JSON format?
Paste your CSV data into the input field. The first row is used as JSON keys (headers), and each subsequent row becomes a JSON object. Click Convert to see the result instantly.
Does it handle CSV files with headers?
Yes. The first row is automatically treated as column headers and used as property names in the JSON output. You can toggle this off if your CSV has no header row.
Can I convert large CSV files?
Yes. Since processing happens in your browser, there are no server upload limits. Performance depends on your device, but files up to several megabytes convert quickly.
Why does my ZIP code lose its leading zero?
Because automatic type detection reads 01234 as the number 1234. Turn typing off, or keep that column as text, when the values are identifiers rather than quantities — postcodes, phone numbers, account references, and product SKUs all break the same way. This is the single most common CSV conversion bug.
Does it handle semicolon-separated files from Excel?
Yes. Excel uses a semicolon in locales where the comma is the decimal separator, which is most of Europe. The delimiter is configurable, and tab-separated files work the same way, so a file exported on a German or Georgian Windows machine converts without editing it first.